Yes, I was just finding that there’s a version sold which uses an STM32L151 to implement an AT command set.
But your data sheet link doesn’t document that AT command set…
The key question would be if the AT command set either already includes LoRaWAN capabilities.
If it does not, then you probably need to replace the STM32 firmware with a customized build of either LMiC or LoRaMAC-node. That is certainly something do-able (and STM32’s are almost always reprogrammable in circuit - chances are those spare and test pads include SWD and/or the pin to enter the bootloader) but could be a moderately advanced project.
There’s also the possibility that the AT command set includes sufficiently low level and time-precise radio commands that a LoRaWAN stack could be made to use those - but this would be a very advanced project, as instead of simply fixing up the I/O operations of a piece of code to run on your controller and board, you’d be changing out all of the low level radio operations.
Unless you have a lot of these you might do better starting with a platform for which LoRaWAN is an already demonstrated capability.